Trailer stabilizer



June 30, 1959 w. w. PARSONS TRAILER STABILIZER Filed March" 8. 1957 4 0a in a 5 Z n, a x

- INV ENT OR. 14441. 752 [16 4230 45 United States Patent 2,892,639TRAILER STABILIZER Walter William Parsons, Montebello, Calif.

Application March 8,1957, Serial No. 644,906

8 Claims. (Cl. 280-460) This invention relates to means for coupling atrailer to an automotive vehicle in a manner to stabilize the traileragainst oscillating movement out of longitudinal alignment with theautomotive vehicle when the trailer is being towed on a substantiallystraight roadway.

The preferred embodiment of the invention comprises stabilizer meanswhich may be sold as an accessory for use with conventional trailerhitches for towing house trailers. This particular embodiment of theinvention has been selected for the present disclosure and will provideadequate guidance for those skilled in the art who may have occasion toapply these same principles to the problem of stabilizing any kind of atrailer.

When a house trailer is coupled to an automobile in a simple pivotalmanner by a' conventional trailer hitch, there is an inherent tendencyfor the trailer to oscillate or sway in opposite lateral directions whendrawn along a straight roadway. The purpose of the presentinvention isto provide damping means to counteract this tendency.

One cause of trailer sway is the lateral forces transmitted to thetrailer from the towing automobile by the trailer hitch. These lateralforces arise from small -de-' partures of the automobile from a straightline of travel and often are augmented by'the fact that the automobileis yieldingly supported by spring means. The swaying of the trailer froma straight line of travel is especially pronounced whenever thefrequency of the lateral forces transmitted thereto from the automobilecoincide with the natural frequency of the trailer body on its springsuspension.

Another cause of sway on the part of a trailer is lateral wind pressure.A gusty side Wind acts on the automobile to augment the lateral forcesthat are transmitted to the trailer through the trailer hitch, and alsoacts on the trailer itself to cause the trailer to oscillate about thetrailer hitch. Here again the effect of the engendered. sway forces ismagnified whenever the frequency of the forces is the natural frequencyof the spring-mounted trailer body.

It has been suggested heretofore in the prior art that a trailer may bedamped or stabilized against sway action by providing a pair of springmeans on opposite sides of the trailer hitch for yielding opposition todeparture of the trailer in opposite directions from longitudinalalignment with the leading automobile. Such arrangements do have astabilizing effect but have a serious inherent disadvantage in that thecounteracting force is of minimum magnitude when the trailer is inlongitudinal alignment with the automobile. The counteracting forceincreases progressively with increasing departure of the trailer fromnormal longitudinal alignment. The rise in resistance with increaseddeparture may seriously interfere with towing the trailer around curvesand corners just when maximum freedom of angular movement of the traileris desirable. A certain dilemma is involved since reducing the force ofthe spring means for the sake of freedom the negotiation of curvesreduces the damping force that is needed for straight travel.

The present invention solves this dilemma by employ- 2,892,639 PatentedJune 30, 1959 ing detent means that provides maximum damping forceagainst initial departure of the trailer from normal longitudinalalignment and alfords much less resistance to changes of the relativeangle of the trailer once the trailer swings out of its normalalignment. The detent means provides direct spring pressure to resistthe initial departure but offers only frictional resistance thereafterto continued departure of the trailer from longitudinal alignment.

A feature of the preferred practice of the invention is theincorporation of stop means in the stabilizer structure. As will beexplained, this provision enables the stabilizer to keep the trailerhitched to the automobile in the event that the trailer hitch failswhile the two vehicles are traveling at high speed.

The various features and advantages of the invention will be readilyunderstood from the following detailed description considered with theaccompanying drawing.

In the drawing, which is to be regarded as merely illustrative:

Fig. 1 is a plan view of an automobile and a coupled house trailerincorporating the presently preferred embodiment of the invention;

Fig. 2 is a side elevation of one of the stabilizer units, viewed asindicated by the arrow 2 in Fig. 1;

Fig. 3 is a horizontal section through the detent means of the unittaken as indicated by the line 33 of Fig. 2;

Fig. 4 is a fragmentary plan view similar to Fig. 1 showing theautomobile and house trailer negotiating a curve; and

Fig. 5 is an end elevation of a modified form of the detent means.

In the drawing, which illustrates the presently preferred embodiment ofthe invention, Fig. 1 shows an automobile 10 towing a house trailer 12by means of a conventional trailer hitch of well known constructiongenerally that is designated by numeral 14. The trailer hitch 14 permitsrelative pivotal movementbetween the automobile and the house trailerabout the axis of a pivot member 15.

The preferred practice of the invention employs two stabilizer units,namely, a right hand unit, designated by the letter R, spaced laterallyfrom the trailer hitch 14 toward the right hand side of the twovehicles, and a left hand stabilizer unit, generally designated by theletter L, spaced laterally from the trailer hitch towards the left handside of the two vehicles. Since each of these stabilizer units has astabilizing effect independently of the other, it is conceivable thatone of the units may be omitted in some practices of the invention.

.As shown in Fig. 2, each of the stabilizer units R and L includes anelongated member or stabilizer rod 20 which, in this instance, is ofround cross-sectional configuration. One end of the stabilizer rod 20 ispivotally connected to one of the two vehicles and the other end of therod slidingly extends through a detent means or detent assembly that isgenerally designated by numeral 22. This detent assembly is pivotallyconnected to the other vehicle. In the particular embodiment of theinvention illustrated by the drawing, the forward end of the stabilizerrod 20 is pivotally connected to the frame of the automobile 10, thestabilizer rod extending rearwardly through the detent assembly 22 andthe detent assembly being pivotally connected to the trailer 12.

As shown in Fig. 2, the forward end of the stabilizer rod 20 isadjustably but rigidly connected to an angular bracket 24 by a pair ofnuts 25 and the bracket is pivotally connected to the frame of theautomobile 10 by a pivot bolt 26. A coiled spring 28 surrounds the pivotbolt 26 in compression between the angular bracket 24 and the automobileframe. It is apparent that the forward end of the stabilizer rod 20 isfree to pivot about the assaese pivot bolt 26 and that the pivot boltmay be removed to disconnect the stabilizer rod from the automobile. Itis also apparent that the two nuts 25 may be adjusted to vary thelongitudinal position of the the stabilizer rod 20.

' The detent assembly 22 through whichthe other end of the stabilizerrod 20 extends has an elongated housing 34 of rectangular configurationand this housing carries a pivot stud 35 that extends rigidly upwardtherefrom for pivotal connection to the trailer. In the arrangementshown in Fig. 2, the pivot stud 35 extends upward through an aperture inan angular bracket 36 that is rigidly mounted on the underside of thetrailer. The pivot stud 35 is retained in the angular bracket 36 bymeans of a nut 38 and a cotter pin 40. Preferably, a coiled spring42'surrounds the pivot stud 35 in compression between the detentassembly housing 3.4 and the angular bracket 36. It is apparent thatthis arrangement permits the stabilizer rod 20 to pivot about the axisof the pivot stud 35 for swinging movement relative to the trailer inaddition to swinging movement relative to the automobile about the pivotbolt 26.

It is contemplated that the stabilizer rod will be peripherally recessedin an appropriate manner for cooperation with the detent assembly 22. Inthis particular embodiment of the invention the detent assembly 22incorporates four detent elements in the form of four steel balls 44,45, 46 and 47, there being two steel balls on each side of the assembly.Accordingly the stabilizer rod 20 has two spherically curved recesses 50and 51 on one side to releasably seat the balls 44 and 45 and has twosimilar recesses 52 and 53 on its'other side to seat the two steel balls46 and 47 when the house trailer l2 is in normal longitudinal alignmentwith the automobile 10.

Each of these steel balls 44, 45, 46 and 47 of the detent assembly 22 iscontinuously pressed inward towards the periphery of the stabilizer rod20 by'a corresponding coiled spring 55. In the construction shown, eachof the coiled springs 55'is confined by a corresponding pipe nipple56'that is closed by an end wall 58 at its outer end and is threadedinto the detent assembly housing 24 in a removable manner. Each of thecoiled springs 55 is in compressionbetween the corresponding steel balland the corresponding end wall 58.

Preferably, the detent housing 34 is slightly larger in cross-sectionaldimension than the stabilizer rod 20 and the stabilizer rod iscentralized in the housing by suitable guide means. For this purpose,the forward end of the detent assembly housing 24 incorporates a guidebushing 60 that slidingly embraces the stabilizer rod 20 and the rearend of' the housing incorporates a second similar guide bushing 62. Ithas been found that incorporation of a third guide means 64 in thehousing structure midway between the two guide bushings is helpful infacilitating assembly, since the lateral thrust exerted by the varioussprings 55 may make it difficult to thread the stabilizer rod throughthe housing.

The preferred practice of the invention is further characterized by theaddition of stop means for cooperation with the detent assembly 22 inthe event that the trailer hitch 14 should fail. For this purpose therear end of the stabilizer rod 20 is provided with an enlargement 66.The stop enlargement 66 is spaced rearwardly from the detent assembly 22by sufiicient distance to avoid contact with the detent assembly at theextreme forward position of the stabilizer rod when the vehicle is beingtowed around a sharp curve. If the trailer hitch 14 should fail,however, the stabilizer rod 20 would be drawn forward to place the stopenlargement 66 in abutment with the rear end of the detent assembly 22whereupon the stabilizer rod would function as a draw bar for keepingthe trailer coupled to the automobile.

The manner in which the invention serves its purpose to stabilize thetravel of a trailer may be readily understood from the foregoingdescription. The detent means comprising the four spring-pressed steelballs provides adequate yielding resistance to relative longitudinalmovement of the two stabilizer bars to withstand the normal range ofrandom forces that tend to make the trailer oscillate out oflongitudinal alignment with the automobile on straight roads. When theautomobile starts to negotiate a curve, however, theresultant forcesapplied to the two stabilizer bars 20 in opposite longitudinaldirections causes one of the stabilizer bars to move forward out ofengagement with its detent means and causes the other stabilizer rod tomove rearward out of engagement with its detent means. When recesses ofthe two stabilizer bars 20 are completely free from the steel balls ofthe two corresponding detent means, the two detent means only lightlyresist relative movements of the two stabilizer rods, the resistancebeing of such low magnitude that it does not interfere with the propertrackingof two stabilizer rods actually makes detent engagement with therod at three different longitudinal positions of the rod. This fact maybe understood by reference to Fig. 3 which shows the stabilizer rod 20in its normal position with the four steel balls yieldingly seated inthe four peripheral recesses. It is apparent that if the stabilizer rod20 is moved to the left in Fig. 3, the ball 44 will be unseated from therod recess 50 but will reseat in the rod recess 51 and, in the samemanner, the steel ball 46 will unseat from the recess 52 and reseat inthe recess 53. Since only two of the four steel balls seat at this timethe resistance of the detent means to longitudinal movement of thestabilizer rod 20 is approximately half of the normal resistance at thenormal position of the stabilizer rod. In the same manner, longitudinalshift of the stabilizer rod 20 to the right from the normal detentposition shown in Fig. 3 will cause the steel ball 45 to shift from itsnormal seat in rod recess 51 into engagement with the rod recess 50 andwill cause the steel ball 47 to shift from the rod recess 53 to the rodrecess 52. v

These additional positions of engagement of the detent means 22 witheach of the two stabilizer rods 20 have a secondary damping efiect inthat they tend to limit the extent to which the trailer sways on thoseoccasions when an exceptional lateral force overcomes the resistance ofthe two detent means at their normal positions of engagement. It is tobe borne in mind that when a trailer oscillates back and forth from itsnormal position of longitudinal alignment with the automobile, arelatively great resistance is required to arrest the oscillation at themid-point of the oscillation but much less resistance is required toarrest the oscillation on either side of the mid-point.

If it is desired to avoid the described secondary damping effect byarranging each of the detent means 22 to engage the correspondingstabilizer rod 20 at only one longitudinal position of the stabilizerrod, it is merely necessary to avoid longitudinal alignment among thestabilizer rod recesses. Fig. 5 for example shows how the four nipples56a may be positioned in four difierent quadrants with the stabilizerrod recesses in the corresponding four quadrants. In such an arrangementonly one stabilizer rod recess is in longitudinal alignment with each ofthe four steel balls. I

My description in specific detail of a selected embodiment of theinvention and of a modification thereof will suggest 'various changes,substitutions and other deof the appended claims.

I claim as my invention:

1. Means to stabilize a trailer vehicle having a central hitchconnection with an automotive vehicle, said stabilizing means including:an elongated member spaced laterally from said bitch connection andhaving at least one peripheral recess; a first means pivotallyconnecting one end of said member with one of said two vehicles; meansslidingly engaging said member for sliding movement relative theretolongitudinally thereof; a second means pivotally connecting said slidingmeans with the other of said two vehicles; detent means carried by saidsliding means normally in yielding engagement with said peripheralrecess with the two vehicles in normal longitudinal alignment therebyoffering relatively high yielding resistance to relative movementbetween the member and the slide means when the two vehicles are innormal longitudinal alignment and relatively low resistance when the twovehicles are out of normal longitudinal alignment with each other.

2. A combination as set forth in claim 1, in which said longitudinalmember has a plurality of longitudinally spaced peripheral recesses andsaid slide means carries a corresponding plurality of detent elementsfor yielding engagement with said recessm when the two vehicles are innormal longitudinal alignment.

3. A combination as set forth in claim 2, in which two of said recessesand two corresponding detent elements are in longitudinal alignmentwhereby both detents engage the two recesses when the two vehicles arein normal longitudinal alignment for maximum resistance to relativemovement between said member and said slide means, and one of saiddetent elements engages one of said recesses for lesser resistance tothe relative movement when the two vehicles are slightly out of normallongitudinal alignment in either lateral direction.

4. A combination as set forth in claim 1, in which said detent meansincludes a ball member and spring means to urge the ball member againstthe periphery 6 of said elongated member for engagement with saidperipheral recess.

5. A combination as set forth in claim 1, in which said first pivotallyconnecting means releasably connects the forward end of said member withsaid automotive vehicle.

6. A combination as set forth in claim 1, which includes a stop on saidelongated member to engage said slide means at a limit position of themember relative to the slide means, thereby to couple the two vehiclestogether in the event said hitch connection fails.

7. Means to stabilize a trailer vehicle as set forth in claim 1, whichincludes two stabilizer assemblies, one on each side of said hitchconnection, each of said assemblies including an elongated member,cooperating slide means, detent means and first and second pivotallyconnecting means.

8. Means to stabilize a trailer vehicle having a central hitchconnection with an automotive vehicle, said stabilizing means including:two elongated members on the 0pposite sides, respectively, of said hitchconnection, each of said members having a detent recess therein; meanspivotally connecting one end of each of said members with one of saidvehicles; and two detent means carried by the other of said vehicles toyieldingly engage said detent recesses respectively when the twovehicles are in normal longitudinal alignment to yieldingly resistinitial movement only of the two vehicles out of normal longitudinalalignment.

References Cited in the file of this patent UNITED STATES PATENTS2,225,130 Otto et a1 Dec. 17, 1940 FOREIGN PATENTS 705,800 Germany May10, 1941

